The Multiple Dimensions of Familiarity: From Representations to Phenomenology.

This article focuses on familiarity, the form of memory allowing humans to recognize stimuli that have been encountered before. We aim to emphasize its complex nature which includes representational and phenomenological dimensions. The former implies that its neural correlates depend on the type and complexity of the cue stimulus, as different classes of stimuli are represented in distributed ventral visual and medial temporal regions.

Cerebral glucose metabolism in Alzheimer's disease.

18F-fluoro-deoxy-glucose positron emission tomography (FDG-PET) is a useful paraclinical exam for the diagnosis of Alzheimer's disease (AD). In this narrative review, we report seminal studies in clinically probable AD that have shown the importance of posterior brain metabolic decrease and the paradoxical variability of the hippocampal metabolism. The FDG-PET pattern was a sensitive indicator of AD in pathologically confirmed cases and it was used for differential diagnosis of dementia conditions.

The Influence of Changes in Daily Life Habits and Well-Being on Fatigue Level During COVID-19 Pandemic.

The COVID-19 pandemic and its lockdown in March 2020 have led to changes in lifestyle and increased levels of anxiety, depression, and fatigue. This survey examined a number of factors (anxiety state, sleep quality, daily activities, mental load, work-related variables) influencing mental and physical fatigue during lockdown and how these relations have evolved one year later. A cohort of 430 workers and 124 retirees were recruited in April-May 2020 (lockdown period, data set 1), and a subsample (133 workers and 40 retirees) completed the same questionnaire in April-May 2021 (data set 2).

An extension of the novelty-seeking model: Considering the plurality of novelty types and their differential interactions with memory.

The novelty-seeking model suggests that curiosity and creativity originate from novelty processes. However, different types of novelty exist, each with distinctive relationships with memory, which potentially influence curiosity and creativity in distinct ways. We thus propose expanding the NSM model to consider these different novelty types and their specific involvement in creativity.

Awareness and cognitive rehabilitation in Alzheimer's disease and frontotemporal dementia.

Introduction: Awareness influences the evolution of neurodegenerative dementias. We gathered participants' and caregivers assessments of dependence in daily activities and we studied how each score would be related to next year participant autonomy, independently of other explicative variables.

Method: We retrospectively analyzed data from mildly demented participants with a clinical diagnosis of Alzheimer's disease (AD, = 186) and frontotemporal dementia (FTD, = 29) and their relatives.

Contextual novelty detection and novelty-related memory enhancement in amnestic mild cognitive impairment.

Introduction: Though novelty processing plays a critical role in memory function, little is known about how it influences learning in memory-impaired populations, such as amnestic Mild Cognitive Impairment (aMCI).

Methods: 21 aMCI patients and 22 age- and education-matched healthy older participants performed two tasks-(i) an oddball paradigm where fractals that were often repeated (60 % of the stimuli), less frequently repeated (20 %), or novel (presented once each) were shown to assess novelty preference (longer viewing time for novel than familiar stimuli), and (ii) a Von Restorff paradigm assessing novelty-related effects on memory. Participants studied 22 lists of 10 words.

Prediction of cognitive decline in healthy aging based on neuropsychiatric symptoms and PET-biomarkers of Alzheimer's disease.

Neuropsychiatric symptoms (NPS) have been associated with a risk of accelerated cognitive decline or conversion to dementia of the Alzheimer's Disease (AD) type. Moreover, the NPS were also associated with higher AD biomarkers (brain tau and amyloid burden) even in non-demented patients. But the effect of the relationship between NPS and biomarkers on cognitive decline has not yet been studied.

Neural correlates of impaired cognitive processes underlying self-unawareness in Alzheimer's disease.

Self-unawareness concerning current symptoms remains a clinical challenge in Alzheimer's disease. Reduced self-awareness likely depends on complex biopsychosocial mechanisms that comprise multiple cognitive processes, regulated by personal goals and values. We specifically reviewed the cognitive processes impaired in unaware participants with AD by emphasizing the related impaired brain activity observed during task-based fMRI.

Neuropsychological predictions on involuntary autobiographical memory and déjà vu.

I strongly support Barzykowski and Moulin in their proposal that common retrieval mechanisms can lead to distinct phenomenological memory experiences. I emphasize the importance of one of these mechanisms, namely the attribution system. Neuropsychological studies should help clarifying the role of these retrieval mechanisms, notably in cases of medial temporal-lobe lesions and cases of dementia.

Multimodal imaging of microstructural cerebral alterations and loss of synaptic density in Alzheimer's disease.

Multiple neuropathological events are involved in Alzheimer's disease (AD). The current study investigated the concurrence of neurodegeneration, increased iron content, atrophy, and demyelination in AD. Quantitative multiparameter magnetic resonance imaging (MRI) maps providing neuroimaging biomarkers for myelination and iron content along with synaptic density measurements using [18F] UCB-H PET were acquired in 24 AD and 19 Healthy controls (19 males).

Locus coeruleus activity while awake is associated with REM sleep quality in older individuals.

BACKGROUNDThe locus coeruleus (LC) is the primary source of norepinephrine in the brain and regulates arousal and sleep. Animal research shows that it plays important roles in the transition between sleep and wakefulness, and between slow wave sleep and rapid eye movement sleep (REMS). It is unclear, however, whether the activity of the LC predicts sleep variability in humans.

Targeting the function of the transentorhinal cortex to identify early cognitive markers of Alzheimer's disease.

Initial neuropathology of early Alzheimer's disease accumulates in the transentorhinal cortex. We review empirical data suggesting that tasks assessing cognitive functions supported by the transenthorinal cortex are impaired as early as the preclinical stages of Alzheimer's disease. These tasks span across various domains, including episodic memory, semantic memory, language, and perception.

Hippocampal metabolic subregions and networks: Behavioral, molecular, and pathological aging profiles.

Introduction: Hippocampal local and network dysfunction is the hallmark of Alzheimer's disease (AD).

Methods: We characterized the spatial patterns of hippocampus differentiation based on brain co-metabolism in healthy elderly participants and demonstrated their relevance to study local metabolic changes and associated dysfunction in pathological aging.

Results: The hippocampus can be differentiated into anterior/posterior and dorsal cornu ammonis (CA)/ventral (subiculum) subregions.

Locus Coeruleus activity while awake is associated with REM sleep quality in healthy older individuals.

The locus coeruleus (LC) is the primary source of norepinephrine (NE) in the brain, and the LC-NE system is involved in regulating arousal and sleep. It plays key roles in the transition between sleep and wakefulness, and between slow wave sleep (SWS) and rapid eye movement sleep (REMS). However, it is not clear whether the LC activity during the day predicts sleep quality and sleep properties during the night, and how this varies as a function of age.

A day that America will remember: flashbulb memory, collective memory, and future thinking for the capitol riots.

This study explores the topics of flashbulb memory, collective identity, future thinking, and shared representations for a public event. We assessed the memories of the Capitol Riots, which happened in Washington DC, on 6 January 2021. Seventy Belgian and seventy-nine American citizens participated in an online study, in which they freely recalled the unfolding of Capitol Riots and answered questions regarding their memory.

Effort during prolonged wakefulness is associated with performance to attentional and executive tasks but not with cortical excitability in late-middle-aged healthy individuals.

Objective: Sleep loss negatively affects brain function with repercussion not only on objective measures of performance but also on many subjective dimensions, including effort perceived for the completion of cognitive processes. This may be particularly important in aging, which is accompanied by important changes in sleep and wakefulness regulation. We aimed to determine whether subjectively perceived effort covaried with cognitive performance in healthy late-middle-aged individuals.

The use of distraction to improve episodic memory in ageing: A review of methods and theoretical implications.

Healthy ageing is characterized by changes in several cognitive functions, including episodic memory and inhibition. While the age-related decrease in the ability to inhibit irrelevant stimuli is often associated with lower performance, especially in episodic memory, some studies have highlighted the boosting effect of distraction in several tasks in older adults, including episodic memory tasks related to recollection. The aim of this article is to review and compare previous studies according to specific study features and to consider the results in light of the dual-process model of recollection and familiarity that were used by the authors of the reviewed articles.

Frontal grey matter microstructure is associated with sleep slow waves characteristics in late midlife.

Study Objectives: The ability to generate slow waves (SW) during non-rapid eye movement (NREM) sleep decreases as early as the 5th decade of life, predominantly over frontal regions. This decrease may concern prominently SW characterized by a fast switch from hyperpolarized to depolarized, or down-to-up, state. Yet, the relationship between these fast and slow switcher SW and cerebral microstructure in ageing is not established.

Timely coupling of sleep spindles and slow waves linked to early amyloid-β burden and predicts memory decline.

Sleep alteration is a hallmark of ageing and emerges as a risk factor for Alzheimer's disease (AD). While the fine-tuned coalescence of sleep microstructure elements may influence age-related cognitive trajectories, its association with AD processes is not fully established. Here, we investigated whether the coupling of spindles and slow waves (SW) is associated with early amyloid-β (Aβ) brain burden, a hallmark of AD neuropathology, and cognitive change over 2 years in 100 healthy individuals in late-midlife (50-70 years; 68 women).

Shared vivid remembering: age-related differences in across-participants similarity of neural representations during encoding and retrieval.

Recent advances in multivariate neuroimaging analyses have made possible the examination of the similarity of the neural patterns of activations measured across participants, but it has not been investigated yet whether such measure is age-sensitive. Here, in the scanner, young and older participants viewed scene pictures associated with labels. At test, participants were presented with the labels and were asked to recollect the associated picture.

I remember it like it was yesterday: Age-related differences in the subjective experience of remembering.

It has been frequently described that older adults subjectively report the vividness of their memories as being as high, or even higher, than young adults, despite poorer objective memory performance. Here, we review studies that examined age-related differences in the subjective experience of memory vividness. By examining vividness calibration and resolution, studies using different types of approaches converge to suggest that older adults overestimate the intensity of their vividness ratings relative to young adults, and that they rely on retrieved memory details to a lesser extent to judge vividness.

Heterogeneity in the links between sleep arousals, amyloid-β, and cognition.

BACKGROUNDTight relationships between sleep quality, cognition, and amyloid-β (Aβ) accumulation, a hallmark of Alzheimer's disease (AD) neuropathology, have been shown. Sleep arousals become more prevalent with aging and are considered to reflect poorer sleep quality. However, heterogeneity in arousals has been suggested while their associations with Aβ and cognition are not established.

Feeling the ease: How the use of oral motor fluency changes in amnesia.

The present study examined the evolution observed in amnesic patients' use of motor fluency when making recognition memory decisions. In this experiment, 9 patients with amnesia and 18 matched controls were presented with two recognition memory tasks composed of 3 types of items: (1) natural words, (2) nonwords difficult to pronounce, and (3) nonwords easy to pronounce, the latter having been shown to be processed in a surprisingly fluent manner as long as participants can articulate them at a subvocal level (i.e.